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<p>On 6 February 2023, two major earthquakes with moment magnitude (<i>M</i><sub>w</sub>) of 7.8 and 7.6 ruptured multiple segments of the Eastern Anatolian Fault system, resulting in many casualties and extensive property damage in Turkey and Syria. The <i>M</i><sub>w</sub> 7.8 earthquake involved bilateral rupture along the Eastern Anatolian Fault, with at least partially supershear rupture towards the northeast and subshear rupture towards the southwest. The cause of this difference in rupture speed remains debated. Here we present evidence from seismic tomographic imaging linking this difference to structural and stress variations along the fault. Specifically, a low-velocity anomaly and a fault-parallel fast velocity direction of anisotropy in the southwest Amanos–Pazarcık segment suggest fluid infiltration, which could facilitate fault creep and reduce the stress loading rate. By contrast, the Erkenek segment to the northeast is associated with a high-velocity anomaly and fault-normal fast velocity direction, suggesting limited fluid infiltration and increased stress accumulation. Hence, we propose that the contrast in stress accumulation explains the discrepancy in rupture speeds in this earthquake and that fault structure in addition to stress loading may influence stress accumulation and thus whether a fault ruptures at supershear speeds.</p>

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High normal stress promoted supershear rupture during the 2023 Mw 7.8 Kahramanmaraş earthquake

  • 期刊论文

  • 发表日期：

    2026年1月6日

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  • Jing Chen,
  • Mijian Xu,
  • Yiming Bai,
  • Shucheng Wu,
  • Xiao Xiao,
  • Shijie Hao,
  • Masaru Nagaso,
  • Hongfeng Yang,
  • Ping Tong

摘要

On 6 February 2023, two major earthquakes with moment magnitude (Mw) of 7.8 and 7.6 ruptured multiple segments of the Eastern Anatolian Fault system, resulting in many casualties and extensive property damage in Turkey and Syria. The Mw 7.8 earthquake involved bilateral rupture along the Eastern Anatolian Fault, with at least partially supershear rupture towards the northeast and subshear rupture towards the southwest. The cause of this difference in rupture speed remains debated. Here we present evidence from seismic tomographic imaging linking this difference to structural and stress variations along the fault. Specifically, a low-velocity anomaly and a fault-parallel fast velocity direction of anisotropy in the southwest Amanos–Pazarcık segment suggest fluid infiltration, which could facilitate fault creep and reduce the stress loading rate. By contrast, the Erkenek segment to the northeast is associated with a high-velocity anomaly and fault-normal fast velocity direction, suggesting limited fluid infiltration and increased stress accumulation. Hence, we propose that the contrast in stress accumulation explains the discrepancy in rupture speeds in this earthquake and that fault structure in addition to stress loading may influence stress accumulation and thus whether a fault ruptures at supershear speeds.